A frequent malady of nonambulatory people such as people confined to beds or wheelchairs is that of the occurrence of decubitus ulcers, frequently referred to as pressure sores or bed sores. A major cause of the disorder is that conventional bedding and wheelchairs provide little in the way of either body support or reduced seating pressure. As there is little support or reduced pressure, the patient's weight exerted essentially constantly on tissue surrounding the skeletal structure can give rise to the formation of decubitus ulcers.
There are generally two types of patient support structures currently available. These structures can be classed as either dynamic or static. Dynamic pads or cushions are those which involve outside power sources to perform their function. Although such systems are convenient for bed confined patients, they are undesirable for wheelchair use due to their lack of mobility. In addition, such dynamic cuhsions are undesirable as they are relatively expensive.
Static cushions are generally preferred due to their being less expensive and their ability to provide mobility such as for use in wheelchairs. The static cushions can be classed into two categories: (1) bladder type cushions and (2) foam cushions.
Bladder type cushions are basically flexible walled bags such as plastic bags which are filled with a fluid or some form of gel. The fluid can be air or water. The gel filled bladders are filled with some type of gel material such as ethylene glycol, polyethylene glycol, silicone, and the like. Bladder type cushions are shown in U.S. Pat. No. 2,434,641 of Burns; and U.S. Pat. Nos. 3,605,145; 3,870,450; and 4,005,236, all of Graebe.
The foam cushions can be any structure using a piece of foam. For example, foam cushions can be solid pieces of foam or some type of foam laminate structure. Examples of foam type cushions are the "egg crate" cushion and the contoured foam cushions. One cushion is disclosed in U.S. Pat. No. 3,231,454 of Williams.
Foam cushions are generally the least expensive type of cushion. The foam cushions are undesirable in that they have a tendency to build up significant amounts of heat. A drawback with the build up of heat is that it is believed that heat buildup is a contributing factor to the occurrence of decubitus ulcers. The bladder products tend to be more expensive and tend to perform better in terms of pressure distribution. Some of the bladder products are low in weight like their counterparts in the foam cushion areas. Bladder products, like the foam cushions, also tend to cause tremendous heat buildup. Another drawback with bladder products is that they tend to elevate the patient to a height greater than foam cushions.
It would be desirable to provide a lightweight, low cost, body support pad which would have the beneficial pressure distribution characteristics of the bladder products as well as the beneficial properties of the foam cushions.